1. Field of the Invention
The present invention relates to a scroll compressor, and more particularly relates to a mechanism to supply oil to an Oldham-ring sliding part.
2. Description of the Related Art
In a scroll compressor as a refrigerant compressor, a frame for supporting a revolving scroll has a key groove to engage with a key provided in an Oldham-ring, and revolution of the revolving scroll is performed by sliding between the key and the key groove. A conventional method of oiling to the sliding part of the Oldham-ring in the frame side is that oil in an oil reservoir provided in the bottom of the compressor is pumped to pass through an oiling hole in the main shaft, and then the oiling to the sliding part of the Oldham-ring depends only on splashing of the oil used in lubrication of the revolving shaft caused by rotation of the balancing weight fixed to the rotating main shaft. A method of more actively splashing the oil with the balancing weight is disclosed in Japanese Patent Application Laid-Open No.58-160582 (1983) where an oil reservoir is provided in the bottom of a back pressure chamber and the oil reserved in the oil reservoir is splashed by centrifugal force of an oiling path provided in the balancing weight in the form of mist. Further, a method of supplying oil not in the form of mist to the sliding part of an Oldham-key in the frame side is disclosed in Japanese Patent Application Laid-Open No.61-135994 (1986) where an oil chamber is provided in the high pressure side of a gastight enclosure and the oil reserved in the oil chamber is supplied to the sliding part of the Oldham-key utilizing the pressure difference between the high pressure side and the back pressure side.
Furthermore, a method of supplying oil the sliding part of an Oldham-key in the frame side is also disclosed in Japanese Patent Application Laid-Open No.61-135994 (1986) where an oil chamber is provided in the high pressure side of a gastight enclosure and the oil reserved in the oil chamber is supplied to the sliding part of the Oldham-key utilizing the pressure difference between the high pressure side and the back pressure side.
In the case where the oiling to the sliding part of the Oldham-ring depends on splashing by the rotating balancing weight among the conventional technologies described above, the oil supplied to the sliding part is in the form of mixed mist. Therefore, the oil attached to the inner wall of the frame above the key groove is reserved in a space formed with the outer part of the end plate of the revolving scroll, the stationary scroll and the frame, and consequently the oil acts as a resistance for the revolving motion of the revolving scroll to decrease the efficiency of the compressor and to cause lack of oil. Further, when it is stopped to supply oil from the oil reservoir in the bottom of the compressor through the oil supplying hole in the main shaft and through the rotating bearing using pressure difference or a pump, there arises a problem in that the rotating bearing and the sliding part of the Oldham-ring are not oiled.
On the other hand, in the case where the oil reserved in the high pressure side is supplied to the back pressure side utilizing the pressure difference, it is difficult to maintain an intermediate pressure in the back pressure chamber. Therefore, although oiling is smoothly performed when the pressure difference is large such as in the initial period of starting the operation of the compressor, oiling does not performed when the operation of the compressor continues long time and accordingly the pressure difference becomes small. Further, in a case where a method of supplying oil from the oil reservoir in the bottom of the compressor utilizing the pressure difference is employed as the lubricating method of the rotating bearing, there is a problem in that oil supplying from the oil reservoir in the bottom of the compressor is stopped if the pressure difference between the delivery pressure and the intermediate pressure cannot be maintained.
When the refrigerant in liquid phase enters into the back pressure chamber, the oil in the sliding part is washed by the cleaning effect of the liquid refrigerant to cause lack of lubrication. Especially, since a refrigerant coping with the earth environment (non-chloric alternative refrigerant) does not have a lubrication effect, supplying of oil is very important comparing with a case of a compressor using a conventional refrigerant.